Question

Phugoid oscillation of an aircraft is

• A. A rapid exchange between wing bending energy and fuselage torsional energy.
• B. A constant exchange between the aircraft's potential energy (altitude) and kinetic energy (airspeed) at a nearly constant angle of attack.
• C. A high-frequency exchange between the horizontal tail's lift and the wing's pitching moment, causing rapid changes in the angle of attack.
• D. An exchange of energy between the lateral side-slip and the directional rolling moment.

Hint:

Aircraft longitudinal dynamic modes: \[ \boxed{ \begin{aligned} \text{Phugoid Mode} &\rightarrow \text{Long period, exchange of PE and KE} \text{Short-period Mode} &\rightarrow \text{Rapid changes in angle of attack and pitch rate} \end{aligned} } \]

Answer 1

The Correct Option is B

Step 1: Recall the definition of phugoid oscillation. A phugoid is a long-period longitudinal oscillation of an aircraft in which there is a continuous exchange between \[ \boxed{\text{Potential Energy}} \] and \[ \boxed{\text{Kinetic Energy}.} \]

Step 2: Identify the characteristics of phugoid motion. During a phugoid oscillation,
• the aircraft alternately gains and loses altitude,
• the airspeed alternately decreases and increases,
• the angle of attack remains nearly constant. Thus, the oscillation is essentially an exchange between altitude and airspeed. Therefore, \[ \boxed{\text{A constant exchange between the aircraft's potential energy and kinetic energy at nearly constant angle of attack}} \] is the correct answer. Thus, \[ \boxed{(B)} \] is the correct answer.